Electronic control or regulation has established its importance in many areas of the system electronics of mobile systems, e.g., in motor vehicles or aircraft. In this context, both digital data exchange (e.g., bus systems), as well as analog signal transmission take place among the components of the system electronics. While appropriate protective measures substantially limit any possible manipulation of participating control units, in principle, signal-transmission, i.e., data-transmission paths can only be protected with great difficulty. In other words, the transmitted information can be manipulated relatively easily.
The need exists, therefore, to not only safeguard the units themselves from an unauthorized external access, but also to protect the data transmission to and from these units from external manipulation attempts. This applies both to the automotive sector (e.g., protection from engine tuning), but to an even greater degree to aircraft. In the automotive sector, it is particularly useful to safeguard the transmission path from the sensors to the control unit and from the control unit to the actuators, the data to be transmitted being available in analog or also in digital form, and in addition to unidirectional data transmission, in particular in the context of control systems, bidirectional data transmission being used as well.